1. Field of the Invention
This invention generally relates to a linear motion rolling contact guide unit, and, in particular, to an anti-vibration linear motion guide unit particularly suitable for use as a drive unit in various machines, such as machining tools, precision processing apparatuses and testing equipment.
2. Description of the Prior Art
A linear motion guide unit having an anti-vibration function is well known as disclosed in the Japanese Utility Model Laid-open Pub. No. 58-6010 and Pat. Laid-open Pub. No. 61-116119. A linear motion guide unit generally includes a rail extending over a desired length, a slider assembly slidably mounted on the rail and a plurality of rolling members interposed between the rail and the slider assembly. In one form of the prior art linear motion guide unit having an anti-vibration function, a friction member is resiliently interposed under pressure between the rail and the slider assembly. In another form of the prior art linear motion guide unit having an anti-vibration function, a dedicated anti-vibration unit is arranged between a pair of ordinary linear motion guide units and a fine gap defined between the dedicated anti-vibration unit and the rail is filled with a lubricant oil to thereby provide a fluiddynamic damper. However, in the former case, since both of the rolling members and the friction member are disposed in the same housing of the slider assembly, there is a limitation in locating the friction member, which in turn imposes limitations in attaining anti-vibration and braking functions and tends to make the structure complicated. In the latter case, because of leakage, difficulty exists in keeping a required amount of lubricating oil in the desired gap.